When connecting with client vulnerability scan program, system cannot switch to root user which is unavailable.
Using installation CD-ROM booting system, and we should press “ALT” to select Linux rescue at the beginning.
Rescue login# root
Check disk partition:
Rescue# fdisk -l
Device Boot Start End Blocks Id System
/dev/sda1 1 1024 1048560 82 Linux swap
/dev/sda2 1025 11264 10485760 83 Linux
Mount disk partition:
Rescue# mount -n / -o remount,rw
Rescue# mount /dev/sda2 /mnt
Rescue# mount -o bind /dev /mnt/dev
Enter /etc/passwd and add:
Save and set root password. Rebooting server can make it normal.
After consulting technologists, we know that the root user is deleted by this program with command “userdel root”.